High-temperature dielectric and microwave absorption performances of TiB2/Al2O3 ceramics prepared by spark plasma sintering

TiB_(2)/Al2O3 ceramics reinforced with Mg O are prepared by spark plasma sintering(SPS).The dielectric and microwave(MW)absorption properties are discussed.The results indicate that both the commercial TiB_(2)(C-TiB_(2))content and preparing temperature play important roles in the dielectric properties.Simultaneously,TiB_(2)/Al2O3 composite shows the best MW absorption property when the C-TiB_(2)content and preparing temperature are 9 wt%and 1400°C.To further improve the MW absorption properties,the composite containing 9 wt%synthesized TiB_(2)(S-TiB_(2))has been sintered at 1400°C.Its high-temperature complex permittivity is greater than that of TiB_(2)/Al2O3 composite with 9 wt%C-TiB_(2)sintered at 1400°C and is directly proportional to the temperature.Besides,TiB_(2)/Al2O3 composite with 9 wt%S-TiB_(2)possesses a better MW absorption at 25–500°C,its effective absorption bandwidth(RL<-5 dB)can reach 4.2 GHz at 25–500°C.And the minimum reflection loss(RLmin)value reaches-43.41 dB at the temperature of 800°C with a thickness of 1.45 mm for TiB_(2)/Al2O3 composite with 9 wt%C-TiB_(2).Consequently,the satisfying absorbing layer(d<1.75 mm),flexural strength,heat stability and considerable high-temperature MW absorption ability grant TiB_(2)/Al2O3 ceramics practical applications as high-temperature microwave absorption materials(MAMs).